The main protagonist. Despite having no esper powers, he has an outstanding intellect. He is 20 years old at the start of the series and is the field leader of "The Children" Special Esper Team, not only giving them directions during missions but also overseeing their daily care. Even as they usually disobey and mistreat him, the girls highly esteem Minamoto, asking to reside with him soon after he is assigned to work with them. Nevertheless, the girls have shown to have grown positively under his watch. While good-natured and tolerant for the most part, there are times when he is pushed over his limits and comically displays an enraged Fist of the North Star-esque demeanor, complete with quotes, inspiring fear even on his superiors or The Children themselves.

(Source: Wikipedia)

In the final arc of the anime he becomes a kid. During this arc Kouichi is voiced by Rie Kugimiya.